Water is the most important element of life since it comprises almost 80% of the human body. In addition, food hygiene depends solely on water, and therefore contamination of water is a common vehicle for the transport of epidemic diseases to humans like Typhoid, food poisoning, and Dysentery. For example, Psychrophilic bacteria's presence in the micro-flora in water can affect refrigerated food and spoil it. Hence, water contamination cannot be overlooked and extreme measures should be taken to assure a high quality of water to sustain life.
With the advent of technology, clean water is becoming a scarce commodity. Water contamination is unequivocally becoming a worldwide problem with unknown ramifications, and billions of U.S. dollars are spent annually to improve its quality. Contamination of waters is not only restricted to industrialized countries, but includes developing nations as well. Therefore, there is an immediate need to find poignant solutions to maintain and preserve water sources.
Recently, there has been a growing interest among scientists and engineers to develop new water and food disinfectant technologies to clean water from dangerous microorganisms. Various methods have been employed which are divided into two categories; namely, physical, chemical, or both. The physical category is represented by techniques utilizing ultrafiltration, reverse osmosis, radiation, freezing, heating, and ultrasound. Although these methods have proved to be effective, the drawbacks include the large electricity requirements and expensive equipment. On the other hand, the chemical category relies on the use of chemical adjuvants which exhibit biocidal properties such as aldehydes, phenols, alcohol, potassium permanganate, and chlorine and certain chlorine containing compounds. Some of these chemicals have many disadvantages associated with them and are now considered poisonous compounds. For instance, people coming into contact with these substances can develop skin irritation and suffer from long time illnesses which in some cases can be fatal; not to mention the unpleasant taste and odor associated with these chemicals. In addition, formation of mutagenic and carcinogenic agents, and genetic resistance are also some of their disadvantages. Notwithstanding, such compounds have afforded a way to battle these harmful microorganisms and their effectiveness have been unequivocally demonstrated.
Other methods have relied upon the use of ultra-violet irradiated silver fluoride solutions containing silver as a source of germicide activities, such as U.S. Pat. No. 3,422,183, incorporated herein in its entirety by reference. However, such techniques require expensive equipment and large amounts of electricity.
Hydrogen peroxide is a strong oxidizing agent, and it has been used for the past 40 years as a disinfectant. Its main advantage is that it does not produce toxic residue or by-products. It has been used ubiquitously as an indirect food additive, as a disinfectant in hospitals, as a decontamination and purification agent of industrial waste water, and as a cleaning agent for exhaust air. Nonetheless, it decomposes readily to form water and oxygen, and has high sensitivity to sunlight and UV rays. Therefore, it is not suited for long-term use since recontamination cannot be circumvented.
In 1880, the Swiss botanist Carl van Nageli observed that highly diluted silver solutions have an algicidal effect. To describe this effect he coined the term “Oligodynamic”. Colloidal silver, which is a pure, all-natural substance consisting of sub-microscopic clusters of silver ions held in suspension in de-ionized water by tiny positive charges on the silver ions, is a powerful prophylactic antibiotic which was used for years with no known side effects. It acts as an inhibitor disabling particular enzymes which bacteria, fungi, and viruses used in their mode of metabolism.
Based on this oligodynamic property, U.S. Pat. No. 4,915,955, incorporated in its entirety herein by reference, combines the germicidal effects of hydrogen peroxide with silver, an inorganic acid, and an organic stabilizer at concentrations of 10-35 mg/l against many forms of bacteria and viruses. The process is based on silver ions, with the aid of hydrogen peroxide, damaging the protective biofilms of these microorganisms. Hence, this method depends solely on killing germs intercellularly. Accordingly, there is a need to develop a new generation of microbicidal agents that overcome one or more of the above-described disadvantages.